Auto monitoring control circuit unit of heat exchanger in air conditioning system

ABSTRACT

An auto monitoring control unit of a heat exchanger an air conditioning system, includes a detecting circuit detecting a heat exchange value at the heat exchanger of the air conditioning system, a reference circuit providing a heat exchange reference for the heat exchanger of the air conditioning system, a processing circuit receiving the heat exchange value from the detecting circuit and comparing the heat exchange value with the heat exchange reference to determine differential value therebetween, a control circuit receiving the differential value from the processing circuit so as to govern the air conditioning system in response to the differential value, and a monitoring circuit electrically connected with the control circuit to monitor the differential value so as to ensure the air conditioning system is functioning in a normal condition.

BACKGROUND OF THE PRESENT INVENTION

[0001] 1. Field of Invention

[0002] The present invention relates to an air conditioning system, andmore particularly to an auto monitoring control unit of a heat exchangerin an air conditioning system, which is capable of promptly andaccurately adjusting heat exchange parameters of the air conditioningsystem so as to ensure efficient operation of that system.

[0003] 2. Description of Related Arts

[0004] Referring to FIG. 1, a schematic diagram of a conventionalcentral air conditioning system which is primarily used for extremelylarge spaces such as shopping malls, commercial buildings, manufacturingplants etc. is illustrated. As shown in FIG. 1, the conventional airconditioning system comprises a compressing device 1, a cooling tower 2,a coolant pump 3, a refrigerant pump 4, and a heat exchange arrangement5.

[0005] The compressing device 1 comprises a condenser 11, a compressor12, and an evaporation device 13. The cooling tower 2 is communicativelyconnected to the condenser 11 through a coolant inlet pipe 111 and acoolant outlet pipe 112 for coolant water passing therethough.Furthermore, the heat exchange arrangement 5 is connected to theevaporation device 13 through a refrigerant inlet pipe 131 and arefrigerant outlet pipe 132. The coolant pump 3 is installed on thecoolant inlet pipe 111 for pumping coolant passing through the coolantinlet pipe 111. On the other hand, the refrigerant pump 4 is installedon the refrigerant inlet pipe 131 for pumping refrigerant passingthrough the refrigerant inlet pipe 131.

[0006] The heat exchange arrangement 5 comprises a cooling coil 51, anda cool air delivering fan 52 communicated with a large space fordelivering refrigerated air coming out from the cooling coil 51 to thatlarge space so as to provide air conditioning. The operation of the airconditioning system is as follows: refrigerant coming out from theevaporation device 13 enters the cooling coil 51 which is essentially aplurality of heat exchangers, wherein heat is extracted from therefrigerated space in the heat exchangers. After passing through theheat exchangers, the refrigerant reenters the evaporation device 13 forcooling. The cycle continues.

[0007] On the other hand, the cooling of the refrigerant is accomplishedby means of evaporation inside the evaporation device 13. The coolantentering the evaporation device 13 is evaporated as heat is extractedfrom the refrigerant. The vapor then leaves the evaporation device 13and then reenters compressor 12 and the condenser 11 where the vaporcondenses into the coolant again. In this condensation process, heat istransferred to ambient air outside the refrigerated space. After that,the coolant is directed to the cooling tower 2 for further reduction oftemperature. In other words, the air conditioning system includes aplurality of heat exchange points between such heat changers for heatexchanging purpose.

[0008] One skilled in the art should recognize that the above-mentionedair conditioning process is of typical nature without introducing novelheat changers and process. There are several deep-seated drawbacksconcerning the above-mentioned conventional air conditioning system—themost notorious one being high electricity consumption. For years,scientists and engineers have been working hard to reduce theelectricity consumption of the air conditioning system. Yet, they mainlyfocus on individual heat changers which make up the air conditioningsystem, thinking like how to reduce the electrical consumption for eachof the individual heat changers. One skilled in the art shouldappreciate that they have really made progress and improved theperformance of most of the heat changers of the air conditioning system.

[0009] However, most of them overlook a significant factor affecting theenergy consumption of the whole air conditioning system which is theactual air conditioning process. Engineering analysis easily revealsthat there are significant drawbacks for conventional refrigeratingsystems and their process:

[0010] First, in designing a particular air conditioning system which ischaracterized by certain refrigerating parameters, such as flow rate ofcoolant and respective power of the pumping devices, a system engineerusually depends on the expected demand of the refrigerating system, plusa safety factor. In other words, the actual system parameters, such asthe power of the pumping devices concerned, will be greater or betterthan required. As a result, unnecessary yet unavoidable, from theengineering's point of view, energy is wasted.

[0011] As an illustration, consider if the actual flow rate of coolantin a particular air conditioning system produced by a particular pumpingdevice, such as a fan, is 267 m³/hr, running at an angular speed of 1750rpm. Take, for example, the desire flow rate of the coolant of the airconditioning system is 190 m³/hr, then, by fan law (derived fromdimensionless analysis), the required angular speed of the fan should be1245 rpm, which is far less than the actual angular speed of 1750 rpm.Moreover, suppose the actual power of the pumping device is 45 kw, bythe fan law again, the required power for the pumping device running at1245 rpm can be calculated as 16.2 kw, which is far less than the actualpumping power. Thus, because of the engineering safety factor, energy isunnecessary, yet ‘unavoidably’ wasted. It would be helpful if one cancontingently control the operational parameters of the pumping device inorder to save energy.

[0012] Second, the air conditioning system usually fails to response tochanging temperature of the incoming air. Very often, when the indoortemperature of the space in which the air conditioning system installsreaches the desirable temperature, the operational parameters of thepumping devices, especially the refrigerant pump 4, remain unchanged.This may make the whole air conditioning system consumes unnecessaryelectrical energy.

[0013] Third, even though the air conditioning system can respond tochanging temperature of the incoming air, due to complicated heattransfer pattern for some highly varying temperature profile situations,such as at the ground floor of a shopping mall where the number ofpeople changes frequently and rapidly, the system may not be able torespond promptly so as to create an optimal operational parameters forthe air conditioning system. As a matter of fact, unnecessary changingof operational parameters can waste as much energy as the system doesnot change them at all. And this is the reason why obtaining an optimalresponse time in the field of Control Engineering, both for mechanicaland electrical systems, is crucial and of overriding importance.

[0014] Fourth, some national engineering standards, such as the ChinaNational Standards (CNS), in air conditioning system suggest that thetemperatures of the cooling tower 2 at the inlet and at the outletshould be 35° C. and 30° C. respectively for most efficient heattransfer. As a result, the cooling tower 2 should be adjusted to obtainthe desirable inlet and outlet coolant temperatures. However, inreality, it is rare that the cooling tower can adjust to such desirableinlet and outlet temperatures because of varying environmentaltemperature. For example, the heat transfer requirement in summer and inwinter is totally difference. Conventional air conditioning systems aremostly too inflexible to adapt to varying environmental circumstances.As a result, unnecessary electricity wastage is incurred.

[0015] From the operators' perspective, for some heavy-duty airconditioning systems, even though some insignificant mechanical failuresoccur, the operators or technicians of such systems can indeed hardlyidentify what is going wrong until an extensive inspection is performed.However, this may not be feasible in that extensive inspection oftenmeans serious interruption of daily operation of the place in which therefrigerating system is installed. Thus, the unnoticed mechanicalfailures may induce significant energy wastage or performancedowngrading. Thus, a self regulating system may be required to fix suchproblems or to adjust operational parameters of the air conditioningsystem for optimal performance, even though during mechanical failure.

[0016] In connection with the operators, most conventional heavy-dutyair conditioning system is incapable of identifying operator's fault soas to induce significant energy wastage. Thus, some sorts of alteringmechanisms may be installed to alert the operators while there issomething wrong with the air conditioning system.

SUMMARY OF THE PRESENT INVENTION

[0017] A main object of the present invention is to provide an automonitoring control unit of a heat exchanger in an air conditioningsystem, which is capable of monitoring operational parameters of all thesystem's heat changers, comparing the operational parameters with a setof standard parameters, and commanding the corresponding system's heatchangers to make suitable changes on those parameters so as to obtainoptimal operation for saving operating energy of the air conditioningsystem.

[0018] Another object of the present invention is to provide an automonitoring control unit of a heat exchanger in an air conditioningsystem, which is capable of illustrating the current operationalparameters of the system's heat changers such that the operators of thatair conditioning system can be able to respond promptly to exceptionalcircumstances or possible mechanical failures.

[0019] Another object of the present invention is to provide an automonitoring control unit of a heat exchanger in an air conditioningsystem, which is capable of identifying any exceptional values of theoperational parameters of the system's heat changers so as to identifythe possible operator's carelessness in operating or repairing the airconditioning system.

[0020] Another object of the present invention is to provide an automonitoring control unit of a heat exchanger in an air conditioningsystem, which neither involves complicated nor expensive mechanical andelectrical heat changers so as to minimize the manufacturing cost andother related expenses in developing the air conditioning system of thepresent invention.

[0021] Accordingly, in order to accomplish the above objects, thepresent invention provides an auto monitoring control unit of a heatexchanger in an air conditioning system, comprising:

[0022] a detecting circuit detecting a heat exchange value at the heatexchanger of the air conditioning system;

[0023] a reference circuit providing a heat exchange reference for theheat exchanger of the air conditioning system;

[0024] a processing circuit receiving the heat exchange value from thedetecting circuit and comparing the heat exchange value with the heatexchange reference to determine differential value therebetween;

[0025] a control circuit receiving the differential value from theprocessing circuit so as to govern the air conditioning system inresponse to the differential value; and

[0026] a monitoring circuit electrically connected with the controlcircuit to monitor the differential value so as to ensure the airconditioning system is functioning in a normal condition.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027]FIG. 1 is a schematic diagram of a conventional air conditioningsystem.

[0028]FIG. 2 is a block diagram of an auto monitoring control unit of aheat exchanger in an air conditioning system according to a preferredembodiment of the present invention.

[0029]FIG. 3 is a circuit diagram of the automatic control system forthe air conditioning system according to the above preferred embodimentof the present invention.

[0030]FIG. 4 is a schematic diagram of a monitoring circuit of the automonitoring control unit of a heat exchanger in an air conditioningsystem according to the above preferred embodiment of the presentinvention, illustrating that a display be shown to the operators.

[0031]FIG. 5 illustrates a first alternative mode of the auto monitoringcontrol unit of a heat exchanger in an air conditioning system accordingto the above preferred embodiment of the present invention.

[0032]FIG. 6 illustrates a second alternative mode of the automonitoring control unit of a heat exchanger in an air conditioningsystem according to the above preferred embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0033] Referring to FIG. 2 of the drawings, an auto monitoring controlunit of a heat exchanger in an air conditioning system according to afirst preferred embodiment of the present invention is illustrated. Asmentioning in the background, the air conditioning system comprises aplurality of heat changers such as an evaporation device, a compressor,a condenser, a cooling tower, and pumping devices.

[0034] The auto monitoring control unit comprises a detecting circuit 80detecting a heat exchange value at each of the heat exchangers of theair conditioning system, a reference circuit 70 providing a heatexchange reference for each of the heat exchangers of the airconditioning system, a processing circuit 60 receiving the heat exchangevalues from the detecting circuit 80 and comparing the heat exchangevalues with the heat exchange references respectively to determinedifferential values therebetween respectively.

[0035] The auto monitoring control unit further comprises a controlcircuit 300 receiving the differential values from the processingcircuit so as to govern the air conditioning system in response to thedifferential values, and a monitoring circuit 90 electrically connectedwith the control circuit 300 to monitor the differential values so as toensure the air conditioning system is functioning in a normal condition.

[0036] According to the preferred embodiment, he detecting circuit 80 isoperatively installed into the air conditioning system at the heatexchanger thereof to measure and obtain the heat exchange values of theair conditioning, such as the temperature at each of the heat exchangersof the air conditioning system before and after every state change. Thedetecting circuit 80 is electrically connected to the processing circuit60 and the monitoring circuit 90 so that any detected parameters in acircuit readable form is sent to the processing circuit 60 and themonitoring circuit 90 for further manipulation as disclosed below.

[0037] The reference circuit 70 is electrically connected to theprocessing circuit 60 and provides the heat exchange reference for eachof the heat exchangers of the air conditioning system wherein each ofthe heat exchange references is a predetermined standard heat exchangevalue in an electronic readable form for each of the heat exchangepoints of the air conditioning system. Therefore, according to the heatexchange references, the air conditioning system is capable offunctioning in a normally optimum condition.

[0038] The processing circuit 60 is arranged to receive the heatexchange values from the detecting circuit 80 and the heat exchangereferences from the reference circuit 70 wherein the processing circuit60 compares the heat exchange values with the heat exchange referencesto form the differential values in an electronic readable formrespectively. The differential values is an algorithm that can be simplydetermined by pure addition or subtraction, or by sophisticated heattransfers equations which require micro-processor to calculate undersome predetermined computer programs. It is worth mentioning that theprocessing circuit 60 is a central control center wherein all othercircuits within the air conditioning system is electrically connectedthereto for data retrieval or manipulation. The differential values arethen transferred to the control circuit 300 and the monitoring circuit90 for further manipulations.

[0039] The control circuit 300 is electrically connected to theprocessing circuit 60 and operatively linked to the heat changer of theair conditioning system so as to adjustably control each of the heatchangers of the air conditioning system in the optimum condition thatthe heat exchange value matches the heat exchange reference. The controlcircuit 300 is arranged to send appropriate controlling signals, whichdepends upon the differential values, to each of the heat changers ofthe air conditioning system so as to regulate the heat transfersparameters of the air conditioning system for optimal or efficientsystem performance. The controlling signal can be something likereducing output power of the pumping devices so that the refrigerantwill be circulated at a lower flow rate. Since the flow rate of therefrigerant significantly affects the amount of heat transferred to andfrom the refrigerant, optimal heat transfer can be achieved by alteringthe flow rate of the refrigerant.

[0040] The monitoring circuit 90 is electrically connected between theprocessing circuit 60, the reference circuit 70 and the detectingcircuit 80 to display the heat exchange values from the detectingcircuit 80, the heat exchange references from the reference circuit 70,and the differential values from the processing circuit 60. The purposeof which is to let the operators of the air conditioning system haveenough and accurate information about the heat transfer parameters sothat any strange values of the heat transfers parameters signalingpossible mechanical or electrical failure can be detected and fixed assoon as possible.

[0041] Referring to FIGS. 3 to 4 of the drawings, the processing circuit60 comprises a microprocessor, such as 8051 chip, the 8052 chip etc.,programmed with fluids mechanics, thermodynamics and heat transfersequations governing the heat transfers within a refrigerating system sothat the detected heat exchange values can be manipulated by thoseprograms to obtain the appropriate set of the differential values.Accordingly, the reference circuit 70 has memories which store thestandardized set of heat transfers parameters. The standards can be theorthodox British Standard (BS) or the International StandardOrganization (ISO), or can be any national standards, depending on theactual situations and the operation venue of the air conditioning systemof the present invention. The heat exchange references are preset as thenormal temperatures of coolant water flowing in and out and the coolantwater flowing in and out through the heat changers of the airconditioning system, and the normal temperatures of the compressor andthe condenser of the air conditioning system.

[0042] The detecting circuit 80 comprises a plurality oftemperature/flow measuring devices 81, such as a plurality ofthermostats or thermometers, operatively installed into the heat changerto measure a desired parameter thereof, an amplifying device 82 foramplifying the measured parameters, and a converter 83 which convertsand sends the parameter, generally analog signal such as temperature indegree Celsius into digital format of equal status, to the processingcircuit 60 and the monitoring circuit 90. The temperature/flow measuringdevices 81 are installed into the air conditioning system at the heatexchangers, i.e. the coolant pump 3, the refrigerant pump 4, thecondenser 11, the evaporation device 13, the coolant inlet and outletpipes 111, 112 of the condenser 11, and the refrigerant inlet and outletpipes 131, 132 of the evaporation device 13 respectively, so as tomeasure, say, the temperature, the heat exchange values of the heatexchangers of the air conditioning system respectively.

[0043] The displaying circuit 90 comprises a display 91, such as a LightEmitting Diode (LED) or a Liquid Crystal Display (LCD), for displayingthe various heat transfer parameters, wherein the display 91 iselectrically connected to the processing circuit 60, the referencecircuit 70 and the detecting circuit 60, as shown in FIG. 3, so as todisplay the heat exchange values from the detecting circuit 80, the heatexchange references from the reference circuit 70 and the differentialvalues from the processing circuit 60.

[0044] As shown in FIG. 4, the display 91 has an optimal figure window911 showing the heat exchange references from the reference circuit 70,an actual figure window 912 showing the heat exchange values from thedetecting circuit 80, a difference window 913 showing the differentialvalues from the processing circuit 60, a plurality of indicating menus914 showing conditions of the heat exchangers of the air conditioningsystem respectively and a function key 915 for selecting the indicatingmenus 914. Accordingly, the indicating menus 914 indicating thetemperatures of heat exchange points of the air conditioning system suchas the coolant water flowing and the coolant water flowing, and volumesthe coolant water and the coolant water. Moreover, each of theindicating menus 914 has an alert light 914 a for alerting any technicalstrange situation leading to possible mechanical or electrical failure.In other words, by controlling the function key 915 to selectivelygovern the heat exchange points of the air conditioning system throughthe indicating menus 914, the heat exchange values at the heatexchangers will be monitored and controlled.

[0045] The control circuit 300 comprises a plurality of reversing logicgates 301 communicatively connected to the processing circuit 60, acurrent amplifier 302 electrically connected to the reversing logicgates 301, and a plurality of relays 303 which are electricallyconnected with current amplifier 302 and arranged to connect to switchesof the heat changers of the air conducting system in such a manner thatwhen the control circuit 300 sends out a control signal to the reversinglogic gates 301, the control signal is send to the relays 303 throughthe current amplifier 302 for controlling the heat changers of the airconditioning system in an on and off manner. It is worth mentioning thatthe switches of the heat changers of the air conditioning systemcomprises a transformer of the compressor 12, a magnetic valve of thecompressor 12, cooling fan 32 of the cooling tower 2, transformers ofthe coolant pump 3 and refrigerant pump 4, and a magnetic switch of theheat exchange arrangement 5.

[0046] The operation of the air conditioning system according to thefirst preferred embodiment of the present invention is elaborated asfollows: When a temperature/flow measuring device 81 of the detectingcircuit 80 has detected the heat exchange value of a particular heatexchanger of the air conditioning system, such as the flow rate of therefrigerant, an analog signal corresponding to that particular heatexchange value is then sent to the amplifying device 82 for amplifyingand then to the converter 83 where the original analog signal isconverted to an electrical signal. The converted electrical signal isthen sent to the monitoring circuit 90 and the processing circuit 60. Inthe processing circuit, the microprocessor retrieves the heat exchangereference at that particular heat exchanger from the reference circuit70 and than compare the heat exchange reference with the heat exchangevalue sent from the converter 83 to generate the differential valuewhich is essentially the difference between the heat exchange value andthe heat exchange reference.

[0047] According to the differential value, and depending on the programbuilt into the microprocessor, it then determines the need to change theheat exchange value by adjusting some physical or electrical propertiesof the concerned individual heat changers of the air conditioningsystem. As an illustration, when the detecting circuit 80 is measuringthe flow rate of the refrigerant while the heat exchange reference ofthe standard flow rate is less than the heat exchange value of theactual flow rate of the refrigerant, it is indicated that therefrigerating process needs to be continue, then, no controlling signalwill be sent to the corresponding relay 303 of the control circuit 300and the system remains unaltered. Moreover, the operator is able tomonitor the condition of the refrigerant by selecting the indicatingmenu 913 via the function key 914 so as to display the correspondingheat exchange values of the flow rate of the refrigerant.

[0048] On the other hand, if the heat exchange reference of the standardflow rate is less than the heat exchange value of the actual flow rateof the refrigerant, it is indicated that the refrigerated space may beover-refrigerated. Therefore, a control signal of lowering down the flowrate of the refrigerant will be sent to the control circuit 300, interms of, say, lowering the pumping power of the pumping device thatcirculates the refrigerant. In other words, the control signal is firstsent to the appropriate reversing logic gate 301, and outputted to therelay 303 that control the power of the pumping device, via theamplifier 302, so that the flow rate of the refrigerant is controlleduntil the heat exchange value reaches the heat exchange reference.

[0049] Moreover, the heat exchange value and the differential value forthat particular heat exchange point are sent to the monitoring circuit90. In other words, the heat exchange value and the differential value,in terms of readable format, such as numerical or usual wordings, areshown to the operators of the air conditioning system for manualmonitoring.

[0050] When the temperature of the refrigerated space substantiallyreaches the desirable level, the temperature of the refrigerant afterpassing through the evaporating device will reach to a certainpredetermined value. Accordingly, when the temperature/flow measuringdevice, say, a thermometer positioned and arranged to measure thetemperature of the refrigerant right after it leaves the evaporatingdevice, a signal will be sent to the processing circuit 60 via theamplifying device 82 and the converter 83. The signal is then comparedwith the heat exchange reference corresponding to a standardtemperature, then, the control signal will be sent to the controlcircuit 300 and finally to the concerned heat exchanger of the airconditioning system. In this case, the power of the compressor will bereduced so as to reduce the refrigerating effect of the system.Therefore, the objective of saving energy under suitable condition canbe accomplished. Of course, when the temperature of the refrigeratedspace is increased again, the auto monitoring control circuit unitshould be able to adjust the corresponding heat changers of the airconditioning system so as to activate the refrigerating process again.

[0051] It is worth mentioning that since the heat exchange referencestored in the reference circuit 70 is in accordance with established andauthoritative engineering standards, large deviation from such data mayrepresent possible mechanical or electrical failure which needtechnicians to fix it manually in order to prevent unnecessaryconsumption of substantial amount of energy. The CNS national standard(CNS 12812, B4075), suggests the heat exchange references that thetemperature of the in-flowing coolant should maintain at 35° C., thetemperature of the out-flowing coolant should maintain at 30° C, thein-flowing refrigerant should maintain at 12° C., and the out-flowingrefrigerant should maintain at 7° C. According to the heat exchangereferences, the air conditioning system is functioning in the best modewhile being energy effective. Moreover, the operator is able to monitorthe air conditioning system through the optimal figure window 911, theactual figure window 912, and the difference window 913 of the display91 so as to control the air conditioning system to reach the optimumcondition manually.

[0052] According to the first preferred embodiment, the above-mentionedexception circumstances may be shown by the following events as detectedby the auto monitoring control circuit unit, note that the followingevents are based on an assumption that the desirable room temperature ofthe refrigerated space is 25° C.:

[0053] 1. When the temperature of the out-flowing refrigerant is greaterthan 7° C., it reflects that there are two possible scenarios: (1.a) thecorresponding temperature/flow measuring device 81 detects that the roomtemperature of the refrigerated space is greater than the desirable roomtemperature of 25° C., i.e. the refrigerated space has not reached thedesirable room temperature, the control circuit 300 will keep the airconditioning system running under monitor; (1.b) after monitoring theair conditioning system for a period of time, if the room temperature isgreater than 25° C. while the temperature of the heat absorbing mediumreaches 7° C., it shows that the heat exchange rate of the cooling coil51 of the heat exchange arrangement 5 cannot reach the optimum perform.Therefore, the operator should clean the cooling 51 to obtain theoptimum perform thereof while being energy effective; (1.c) aftercleaning the cooling coil 51, if the room temperature is still greaterthan 25° C. while the temperature of the heat absorbing medium reaches7° C., it shows that mechanical failure of the heat exchangers or otherheat changers of the air conditioning system. The operator is able tocheck the heat changers connected to the heat exchanger arrangement 5 inorder to fix the problem.

[0054] 2. When the temperature of the out-flowing refrigerant is lessthan 7° C., it reflects that the room temperature of the refrigeratedspace reaches 25° C. Therefore, the control circuit 300 willautomatically send the control signal to the air conditioning system asfollow: (2.a) automatically higher the temperature of the refrigerant tominimize the flow rate of the heat absorbing medium to the compressor 12so as to minimize the work done by the compressor 12 while being energyeffective; (2.b) automatically higher the temperature of the refrigerantand lowing the cycling rate of the refrigerant to minimize the work doneby the refrigerant pump 4 and the compressor 12; or (2.c) automaticallylowering the cycle rate to minimize the rpm of the refrigerant pump 4 soas to minimize the work done by the refrigerant pump 4 while beingenergy effective.

[0055] 3. When the temperature of the out-flowing refrigerant is greaterthan 12° C., it reflects there are three possible scenarios: (3.a) thetemperature of the refrigerated space has not yet reached the desirable25° C., in this case, the control circuit 300 will allow therefrigerating process continues; (3.b) there is possible mechanicalfailure at the heat exchangers if the refrigerated space has temperaturegreater than 25° C., in this case, the cooling coil 51 of the heatexchange arrangement 5 need cleaning or repairing; (3.c) there arepossible mechanical failures of individual heat changers of the airconditioning if after cleaning or repairing of the cooling coil 51, theroom temperature is still greater than 25° C.

[0056] 4. When the temperature of the out-flowing refrigerant is lessthan 12° C., it reflects that the temperature of the refrigerated spacereaches the desirable 25° C., thus, the controlling circuit will do oneof the followings: (4.a) automatically higher the temperature of therefrigerant to minimize the flow rate of the refrigerant to thecompressor 12 so as to minimize the work done by the compressor 12 whilebeing energy effective; (4.b) automatically higher the temperature ofthe refrigerant and lowing the cycling rate of the refrigerant tominimize the work done by the refrigerant pump 4 and the compressor 12;or (4.c) automatically lowering the cycle rate to minimize the rpm ofthe refrigerant pump 4 so as to minimize the work done by therefrigerant pump 4 while being energy effective.

[0057] 5. When the temperature of the out-flowing coolant is greaterthan 35° C., it reflects that the temperature of the coolant is too highthat the heat exchanger of the cooling tower 2 is not efficient and thecompressing device 1 cannot reach its optimum performance. Therefore,the operator should appropriate inspect the tension of the belt of thefan 23 of the cooling tower 2 or whether the air inlet of the coolingtower 2 is stuck. In other words, by detecting the temperature of thecoolant, the present invention ensures the cooling tower 2 functioningproperly and efficiently.

[0058] 6. When the temperature of the out-flowing coolant is less than35° C., it reflects that the heat exchanger of the cooling tower 2 isrunning effectively.

[0059] 7. When the temperature of the in-flowing coolant is greater than30° C., which is too high, it reflects that the heat exchanger of thecooling tower 2 is ineffective and the compressing device 1 isfunctioning inefficient. Therefore, the operator should appropriateinspect the tension of the belt of the fan 23 of the cooling tower 2 orwhether the air inlet of the cooling tower 2 is stuck in order to solvethe above problems.

[0060] 8. When the temperature of the in-flowing coolant is less than30° C., it reflects that the heat exchange of the cooling tower 2 isrunning effectively.

[0061] 9. One skilled in the art should realize that the evaporatingtemperature of the heat absorption medium must be lower than thetemperature of the out-flowing refrigerant, whereas the condensationtemperature of the heat absorption medium must be higher than thetemperature of the out-flowing coolant. Conventionally, the evaporatingtemperature of the heat absorption medium is preferably 2° C. lower thanthe temperature of the out-flowing refrigerant, whereas the condensationtemperature of the refrigerant is 2° C. higher than the temperature ofthe out-flowing coolant. According to the preferred embodiment, theevaporating temperature of the heat absorption medium is set as 5° C.,whereas condensation temperature of the heat absorption medium is set as37° C. As a result, when the evaporating temperature of the heatabsorption medium is higher than 5° C., it reflects that the temperatureof the refrigerated space has not reached the desirable 25° C., thecontrol circuit 300 should allow the refrigerating process to continue.

[0062] 10. When the evaporating temperature of the heat absorptionmedium is less than 5° C., it reflects that the compressing device 1 isrunning at a low efficiency, operator's investigation is requiredwhether the refrigerant is leaking or not.

[0063] 11. When the condensation temperature of the heat absorptionmedium is greater than 37° C., it reflects that the temperature of thecoolant is too high such that the heat exchange of the cooling tower 2is ineffective and the compressing device 1 is functioning inefficient.Therefore, the operator should appropriate inspect the tension of thebelt of the fan 23 of the cooling tower 2 or whether the air inlet ofthe cooling tower 2 is stuck in order to solve the above problems.

[0064] 12. When the condensation temperature of the heat absorptionmedium is less than 37° C., it reflects that the cooling tower isrunning properly, the control circuit 300 will thus allow therefrigerating process to continue.

[0065] Note that the temperature/flow measuring device 81 of thedetecting circuit 80 will send the heat exchange value to the controlcircuit 300 for switching on the fan 23 of the cooling tower 2 when thetemperature/flow measuring device 81 detects the temperature of theout-flowing coolant is the same as that of the in-flowing coolant whilethe fan 23 of the cooling tower 2 is switch off due to the check up.Therefore, the present invention provides an indication of objectivefigures which can lead to subjective diagnosis of the possible failureof the air conditioning system.

[0066]FIG. 5 illustrates a first alternative mode of the auto monitoringcontrol circuit unit according to the preferred embodiment of thepresent invention, wherein the auto monitoring control circuit unitfurther comprises means 100 for generating a warning signal when one ofthe differential values is out of a safety range that preset in theprocessing circuit 60. Accordingly, the warning signal means 100 is avoice alerting circuit electrically connected to the processing circuit60. Specifically, the warning signal means 100 comprises a verbalanalysis integrated chip (IC) 101, a speaker activation circuit 102, anda voice producing device 103. When the processing circuit 60 hasdetermined that an exceptional circumstance occurs as mentioned above,in addition to controlling the concerned heat changers of the airconditioning system, it will send the warning signal to the verbalanalysis IC 101 which then activates the speaker activation circuit 102to drive the voice producing device 103 to produce a predeterminedformat of verbal warning signal. Therefore, the operator is able todetermine a possible failure of the air conditioning system as soon aspossible.

[0067]FIG. 6 illustrates a second alternative of the auto monitoringcontrol circuit unit, which further comprises means 200 for manuallyinputting heat exchange data as the heat exchange reference in theprocessing circuit 60. The inputting means 200 is an input circuitelectrically connected to the processing circuit 60 wherein theinputting means 200 comprises an input operator 201, such as a keyboard,for a user of the air conditioning system to key in the heat exchangedate in the processing circuit 60. Thus, the air conditioning system ofthe present invention is capable of adapting various standards so as tofit actual operation circumstances. Accordingly, the inputting means 200can further comprises a clear operator 203 and a setup operator 202 toerase the original heat exchange references in the processing circuit 60and to configure the heat exchange data as the heat exchange referencein the processing circuit 60 respectively.

[0068] In view of above, the auto monitoring control circuit unit of thepresent invention can effectively governing the entire air conditioningsystem by detecting the beat exchange values at the heat exchangers ofthe air condition system and comparing the heat exchange values with theheat exchange references respectively. Therefore, in response to thedifferential values, the control circuit 300 can effectively control theheat changers of the air conditioning system in an on and off manner soas to guide the air conditioning system in the optimum performance whilebeing energy effective. Thus, the auto monitoring control circuit unitof the present invention can diagnosis of the possible failure of theair conditioning system due to the manual mistake.

What is claimed is:
 1. An auto monitoring control circuit unit of a heatchanger in an air conditioning system, comprising: a detecting circuitdetecting a heat exchange value at said heat exchanger of said airconditioning system; a reference circuit providing a heat exchangereference for said heat exchanger of said air conditioning system; aprocessing circuit receiving said heat exchange value from saiddetecting circuit and comparing said heat exchange value with said heatexchange reference to determine differential value therebetween; acontrol circuit receiving said differential value from said processingcircuit so as to govern said heat changer of said air conditioningsystem in response to said differential value; and a monitoring circuitelectrically connected with said control circuit to monitor saiddifferential value so as to ensure said heat changer of said airconditioning system is functioning in an optimum condition in responseto said heat exchange reference.
 2. The auto monitoring control circuitunit, as recited in claim 1, wherein said detecting circuit comprises atleast a temperature/flow measuring device operatively installed intosaid heat changer to measure a desired parameter thereof, an amplifyingdevice for amplifying said parameter of said heat changer, and aconverter converting and sending said parameter to said processingcircuit.
 3. The auto monitoring control circuit unit, as recited inclaim 1, wherein said reference value is stored in said referencecircuit and arranged in such a manner that when said heat changerperforms under said reference value, said air conditioning systemfunctions in said optimum condition.
 4. The auto monitoring controlcircuit unit, as recited in claim 2, wherein said reference value isstored in said reference circuit and arranged in such a manner that whensaid heat changer performs under said reference value, said airconditioning system functions in said optimum condition.
 5. The automonitoring control circuit unit, as recited in claim 1, wherein saidcontrol circuit comprises at least a reversing logic gatecommunicatively connected to said processing circuit, a currentamplifier electrically connected to said reversing logic gate, and atleast a relay which is electrically connected between said currentamplifier and said heat changer in such a manner that when said controlcircuit sends out a control signal to said reversing logic gate, saidcontrol signal is amplified and sent to said relay through said currentamplifier so as to adjustably control said heat changer in an on and offmanner.
 6. The auto monitoring control circuit unit, as recited in claim2, wherein said control circuit comprises at least a reversing logicgate communicatively connected to said processing circuit, a currentamplifier electrically connected to said reversing logic gate, and atleast a relay which is electrically connected between said currentamplifier and said heat changer in such a manner that when said controlcircuit sends out a control signal to said reversing logic gate, saidcontrol signal is amplified and sent to said relay through said currentamplifier so as to adjustably control said heat changer in an on and offmanner.
 7. The auto monitoring control circuit unit, as recited in claim4, wherein said control circuit comprises at least a reversing logicgate communicatively connected to said processing circuit, a currentamplifier electrically connected to said reversing logic gate, and atleast a relay which is electrically connected between said currentamplifier and said heat changer in such a manner that when said controlcircuit sends out a control signal to said reversing logic gate, saidcontrol signal is amplified and sent to said relay through said currentamplifier so as to adjustably control said heat changer in an on and offmanner.
 8. The auto monitoring control circuit unit, as recited in claim1, wherein said monitoring circuit comprises a display which iselectrically connected to said processing circuit and comprises anoptimal figure window for showing said heat exchange reference from saidreference unit, an actual figure window for showing said heat exchangevalue from said detecting circuit, and a difference window for showingsaid differential value from said processing circuit.
 9. The automonitoring control circuit unit, as recited in claim 2, wherein saidmonitoring circuit comprises a display which is electrically connectedto said processing circuit and comprises an optimal figure window forshowing said heat exchange reference from said reference unit, an actualfigure window for showing said heat exchange value from said detectingcircuit, and a difference window for showing said differential valuefrom said processing circuit.
 10. The auto monitoring control circuitunit, as recited in claim 4, wherein said monitoring circuit comprises adisplay which is electrically connected to said processing circuit andcomprises an optimal figure window for showing said heat exchangereference from said reference unit, an actual figure window for showingsaid heat exchange value from said detecting circuit, and a differencewindow for showing said differential value from said processing circuit11. The auto monitoring control circuit unit, as recited in claim 5,wherein said monitoring circuit comprises a display which iselectrically connected to said processing circuit and comprises anoptimal figure window for showing said heat exchange reference from saidreference unit, an actual figure window for showing said heat exchangevalue from said detecting circuit, and a difference window for showingsaid differential value from said processing circuit.
 12. The automonitoring control circuit unit, as recited in claim 7, wherein saidmonitoring circuit comprises a display which is electrically connectedto said processing circuit and comprises an optimal figure window forshowing said heat exchange reference from said reference unit, an actualfigure window for showing said heat exchange value from said detectingcircuit, and a difference window for showing said differential valuefrom said processing circuit.
 13. The auto monitoring control circuitunit, as recited in claim 7, further comprises means for generating awarning signal when said differential value is out of a safety rangepreset in said processing circuit.
 14. The auto monitoring controlcircuit unit, as recited in claim 12, further comprises means forgenerating a warning signal when said differential value is out of asafety range preset in said processing circuit.
 15. The auto monitoringcontrol circuit unit, as recited in claim 13, wherein said warningsignal means comprises a voice alerting circuit electrically connectedto said processing means, and comprises a verbal analysis integratedchip, a speaker activation circuit, and a voice producing device,wherein in response to an unusual operational condition, said warningsignal is sent from said processing means to said verbal analysisintegrated chip which is capable of activating said speaker activationcircuit to activate said voice producing device to produce apredetermined format of verbal alert.
 16. The auto monitoring controlcircuit unit, as recited in claim 14, wherein said warning signal meanscomprises a voice alerting circuit electrically connected to saidprocessing means, and comprises a verbal analysis integrated chip, aspeaker activation circuit, and a voice producing device, wherein inresponse to an unusual operational condition, said warning signal issent from said processing means to said verbal analysis integrated chipwhich is capable of activating said speaker activation circuit toactivate said voice producing device to produce a predetermined formatof verbal alert.
 17. The auto monitoring control circuit unit, asrecited in claim 7, further comprising means for manually inputting heatexchange data as said heat exchange reference in said processingcircuit.
 18. The auto monitoring control circuit unit, as recited inclaim 12, further comprising means for manually inputting heat exchangedata as said heat exchange reference in said processing circuit.
 19. Theauto monitoring control circuit unit, as recited in claim 17, whereinsaid inputting means comprises an input operator for keying in said heatexchange data in said processing circuit, a clear operator for erasingan original heat exchange reference in said processing circuit, and asetup operator for configuring said heat exchange data as said heatexchange reference in said processing circuit.
 20. The auto monitoringcontrol circuit unit, as recited in claim 18, wherein said inputtingmeans comprises an input operator for keying in said heat exchange datain said processing circuit, a clear operator for erasing an originalheat exchange reference in said processing circuit, and a setup operatorfor configuring said heat exchange data as said heat exchange referencein said processing circuit.